There is a variety of nice results about strongly Gorenstein flat modules over coherent rings. These results are done by Ding, Lie and Mao. The aim of this paper is to generalize some of these results, and to give hom...There is a variety of nice results about strongly Gorenstein flat modules over coherent rings. These results are done by Ding, Lie and Mao. The aim of this paper is to generalize some of these results, and to give homological descriptions of the strongly Gorenstein flat dimension (of modules and rings) over arbitrary associative rings.展开更多
When the base connected cochain DG algebra is cohomologically bounded, it is proved that the difference between the amplitude of a compact DG module and that of the DG algebra is just the projective dimension of that ...When the base connected cochain DG algebra is cohomologically bounded, it is proved that the difference between the amplitude of a compact DG module and that of the DG algebra is just the projective dimension of that module. This yields the unboundedness of the cohomology of non-trivial regular DG algebras.When A is a regular DG algebra such that H(A) is a Koszul graded algebra, H(A) is proved to have the finite global dimension. And we give an example to illustrate that the global dimension of H(A) may be infinite, if the condition that H(A) is Koszul is weakened to the condition that A is a Koszul DG algebra. For a general regular DG algebra A, we give some equivalent conditions for the Gorensteiness.For a finite connected DG algebra A, we prove that Dc(A) and Dc(A op) admit Auslander-Reiten triangles if and only if A and A op are Gorenstein DG algebras. When A is a non-trivial regular DG algebra such that H(A) is locally finite, Dc(A) does not admit Auslander-Reiten triangles. We turn to study the existence of Auslander-Reiten triangles in D lf b (A) and D lf b (A op) instead, when A is a regular DG algebra.展开更多
We generalize the concept -- dimension tree and the related results for monomial algebras to a more general case -- relations algebras A by bringing GrSbner basis into play. More precisely, we will describe the minima...We generalize the concept -- dimension tree and the related results for monomial algebras to a more general case -- relations algebras A by bringing GrSbner basis into play. More precisely, we will describe the minimal projective resolution of a left A-module M as a rooted ＇weighted＇ diagraph to be called the minimal resolution graph for M. Algorithms for computing such diagraphs and applications as well will be presented.展开更多
For a local commutative Gorenstein ring R,Enochs et al.in[Gorenstein projective resolvents,Comm.Algebra 44(2016)3989-4000)defined a functor Extn^(R)(-,-)and showed that this functor can be computed by taking a totally...For a local commutative Gorenstein ring R,Enochs et al.in[Gorenstein projective resolvents,Comm.Algebra 44(2016)3989-4000)defined a functor Extn^(R)(-,-)and showed that this functor can be computed by taking a totally acyclic complex arising from a projective coresolution of the first component or a totally acyclic complex arising from a projective resolution of the second component.In order to define the functor Extn^(R)(-,-)over general rings,we introduce the right Gorenstein projective dimension of an R-module M,RGpd(M),via Gorenstein projective coresolutions,and give some equivalent characterizations for the finiteness of RGpd(M).Then over a general ring R we define a co-Tate homology group Extn^(R)(-,-) for R-modules M and N with RGpd(M)<oo and Gpd(N)<∞,and prove that Extn^(R)(M,N)can be computed by complete projective coresolutions of the first variable or by complete projective resolutions of the second variable.展开更多
In this paper, it is proved that the global dimension of a Yetter-Drinfel’d Hopf algebra coincides with the projective dimension of its trivial module k.
In this paper,we generalize the idea of Song,Zhao and Huang[Czechoslov.Math.J.,70,483±504(2020)]and introduce the notion of right(left)Gorenstein subcategory rg(l,∂)(lg(l,D)),relative to two additive full subcate...In this paper,we generalize the idea of Song,Zhao and Huang[Czechoslov.Math.J.,70,483±504(2020)]and introduce the notion of right(left)Gorenstein subcategory rg(l,∂)(lg(l,D)),relative to two additive full subcategoriesφand∂of an abelian category A.Under the assumption thatφ⊆∂,we prove that the right Gorenstein subcategory rg(l,D)possesses many nice properties that it is closed under extensions,kernels of epimorphisms and direct summands.Whenφ⊆Dandφ⊥D,we show that the right Gorenstein subcategory rg(l,D)admits some kind of stability.Then we discuss a resolution dimension for an object in A,called rg(l,D)-projective dimension.Finally,we prove that if(U,V)is a hereditary cotorsion pair with kernelφhas enough injectives,such that U⊆Dand U⊥∂,then(rg(l,D),φφ)is a weak Auslander±Buchweitz context,whereφis the subcategory of A consisting of objects with finiteφ-projective dimension.展开更多
In this paper,from the Anick’s resolution and Grobner-Shirshov basis for quantized enveloping algebra of type C_(3),we compute the minimal projective resolution of the trivial module U_(q)+(C_(3))and as an applicatio...In this paper,from the Anick’s resolution and Grobner-Shirshov basis for quantized enveloping algebra of type C_(3),we compute the minimal projective resolution of the trivial module U_(q)+(C_(3))and as an application,we obtain that the global dimension of U_(q)+(C_(3))is 9.展开更多
Let (R, m) be a local GCD domain. R is called a U 2 ring if there is an element u ∈ m ? m2 such that R/(u) is a valuation domain and R u is a Bézout domain. In this case u is called a normal element of R. In thi...Let (R, m) be a local GCD domain. R is called a U 2 ring if there is an element u ∈ m ? m2 such that R/(u) is a valuation domain and R u is a Bézout domain. In this case u is called a normal element of R. In this paper we prove that if R is a U 2 ring, then R and R[x] are coherent; moreover, if R has a normal element u and dim(R/(u)) = 1, then every finitely generated projective module over R[X] is free.展开更多
For a commutative Noetherian local ring A, we have the following proposition: A is aGorenstein ring if and only if for all finitely generated A-modules M, id_AM^-is finite if andonly if pd_AM is finite. Now, we consid...For a commutative Noetherian local ring A, we have the following proposition: A is aGorenstein ring if and only if for all finitely generated A-modules M, id_AM^-is finite if andonly if pd_AM is finite. Now, we consider the following property: given a Noetherian localring A, for an arbitrary finitely generated A-module M, id_AM is finite, implying that pd_AMis finite. We ask: what ring is characterized by the above property? In this note, we firstconsider the above question; then for commutative Noetherian ring A (not necessarily lo-展开更多
In Ref. [1], Yao demonstrates that the projective dimension of a simple module over a commutative Noetherian ring equals its injective dimension and characterizes the commutative ring possessing an injective simple mo...In Ref. [1], Yao demonstrates that the projective dimension of a simple module over a commutative Noetherian ring equals its injective dimension and characterizes the commutative ring possessing an injective simple module. In this note, we consider a similar problem and generalize the main result of Ref. [1].展开更多
We introduce the n-pure projective(resp.,injective)dimension of complexes in n-pure derived categories,and give some criteria for computing these dimensions in terms of the n-pure projective(resp.,injective)resolution...We introduce the n-pure projective(resp.,injective)dimension of complexes in n-pure derived categories,and give some criteria for computing these dimensions in terms of the n-pure projective(resp.,injective)resolutions(resp.,coresolutions)and n-pure derived functors.As a consequence,we get some equivalent characterizations for the finiteness of n-pure global dimension of rings.Finally,we study Verdier quotient of bounded n-pure derived category modulo the bounded homotopy category of n-pure projective modules,which is called an n-pure singularity category since it can reflect the finiteness of n-pure global dimension of rings.展开更多
文摘There is a variety of nice results about strongly Gorenstein flat modules over coherent rings. These results are done by Ding, Lie and Mao. The aim of this paper is to generalize some of these results, and to give homological descriptions of the strongly Gorenstein flat dimension (of modules and rings) over arbitrary associative rings.
基金supported by the National Natural Science Foundation of China (Grant No. 10731070)the Doctorate Foundation of Ministry of Education of China (Grant No. 20060246003)
文摘When the base connected cochain DG algebra is cohomologically bounded, it is proved that the difference between the amplitude of a compact DG module and that of the DG algebra is just the projective dimension of that module. This yields the unboundedness of the cohomology of non-trivial regular DG algebras.When A is a regular DG algebra such that H(A) is a Koszul graded algebra, H(A) is proved to have the finite global dimension. And we give an example to illustrate that the global dimension of H(A) may be infinite, if the condition that H(A) is Koszul is weakened to the condition that A is a Koszul DG algebra. For a general regular DG algebra A, we give some equivalent conditions for the Gorensteiness.For a finite connected DG algebra A, we prove that Dc(A) and Dc(A op) admit Auslander-Reiten triangles if and only if A and A op are Gorenstein DG algebras. When A is a non-trivial regular DG algebra such that H(A) is locally finite, Dc(A) does not admit Auslander-Reiten triangles. We turn to study the existence of Auslander-Reiten triangles in D lf b (A) and D lf b (A op) instead, when A is a regular DG algebra.
文摘We generalize the concept -- dimension tree and the related results for monomial algebras to a more general case -- relations algebras A by bringing GrSbner basis into play. More precisely, we will describe the minimal projective resolution of a left A-module M as a rooted ＇weighted＇ diagraph to be called the minimal resolution graph for M. Algorithms for computing such diagraphs and applications as well will be presented.
基金Supported by National Natural Science Foundation of China(Grant No.11971388).
文摘For a local commutative Gorenstein ring R,Enochs et al.in[Gorenstein projective resolvents,Comm.Algebra 44(2016)3989-4000)defined a functor Extn^(R)(-,-)and showed that this functor can be computed by taking a totally acyclic complex arising from a projective coresolution of the first component or a totally acyclic complex arising from a projective resolution of the second component.In order to define the functor Extn^(R)(-,-)over general rings,we introduce the right Gorenstein projective dimension of an R-module M,RGpd(M),via Gorenstein projective coresolutions,and give some equivalent characterizations for the finiteness of RGpd(M).Then over a general ring R we define a co-Tate homology group Extn^(R)(-,-) for R-modules M and N with RGpd(M)<oo and Gpd(N)<∞,and prove that Extn^(R)(M,N)can be computed by complete projective coresolutions of the first variable or by complete projective resolutions of the second variable.
基金supported by National Natural Science Foundation of China (Grant No. 10726039)the Leading Academic Discipline Program and 211 Project for Shanghai University of Finance and Economics (the 3rd phase)
文摘In this paper, it is proved that the global dimension of a Yetter-Drinfel’d Hopf algebra coincides with the projective dimension of its trivial module k.
基金Supported by National Natural Science Foundation of China(Grant No.11971225)。
文摘In this paper,we generalize the idea of Song,Zhao and Huang[Czechoslov.Math.J.,70,483±504(2020)]and introduce the notion of right(left)Gorenstein subcategory rg(l,∂)(lg(l,D)),relative to two additive full subcategoriesφand∂of an abelian category A.Under the assumption thatφ⊆∂,we prove that the right Gorenstein subcategory rg(l,D)possesses many nice properties that it is closed under extensions,kernels of epimorphisms and direct summands.Whenφ⊆Dandφ⊥D,we show that the right Gorenstein subcategory rg(l,D)admits some kind of stability.Then we discuss a resolution dimension for an object in A,called rg(l,D)-projective dimension.Finally,we prove that if(U,V)is a hereditary cotorsion pair with kernelφhas enough injectives,such that U⊆Dand U⊥∂,then(rg(l,D),φφ)is a weak Auslander±Buchweitz context,whereφis the subcategory of A consisting of objects with finiteφ-projective dimension.
基金Supported by the National Natural Science Foundation of China(Grant No.11971384)the Natural Science Foundation of Shaanxi Province(Grant No.2021JQ-894)。
文摘In this paper,from the Anick’s resolution and Grobner-Shirshov basis for quantized enveloping algebra of type C_(3),we compute the minimal projective resolution of the trivial module U_(q)+(C_(3))and as an application,we obtain that the global dimension of U_(q)+(C_(3))is 9.
基金supported by the National Natural Science Foundation of China (Grant No. 10671137)the Ph. D. Programs Foundation of Ministry of Education of China (Grant No. 20060636001)
文摘Let (R, m) be a local GCD domain. R is called a U 2 ring if there is an element u ∈ m ? m2 such that R/(u) is a valuation domain and R u is a Bézout domain. In this case u is called a normal element of R. In this paper we prove that if R is a U 2 ring, then R and R[x] are coherent; moreover, if R has a normal element u and dim(R/(u)) = 1, then every finitely generated projective module over R[X] is free.
基金Project supported by the National Natural Science Foundation of China.
文摘For a commutative Noetherian local ring A, we have the following proposition: A is aGorenstein ring if and only if for all finitely generated A-modules M, id_AM^-is finite if andonly if pd_AM is finite. Now, we consider the following property: given a Noetherian localring A, for an arbitrary finitely generated A-module M, id_AM is finite, implying that pd_AMis finite. We ask: what ring is characterized by the above property? In this note, we firstconsider the above question; then for commutative Noetherian ring A (not necessarily lo-
文摘In Ref. [1], Yao demonstrates that the projective dimension of a simple module over a commutative Noetherian ring equals its injective dimension and characterizes the commutative ring possessing an injective simple module. In this note, we consider a similar problem and generalize the main result of Ref. [1].
基金Supported by National Natural Science Foundation of China(Grant No.11871125)Natural Science Foundation of Chongqing(Grant No.cstc2021jcyj-msxm X0048)。
文摘We introduce the n-pure projective(resp.,injective)dimension of complexes in n-pure derived categories,and give some criteria for computing these dimensions in terms of the n-pure projective(resp.,injective)resolutions(resp.,coresolutions)and n-pure derived functors.As a consequence,we get some equivalent characterizations for the finiteness of n-pure global dimension of rings.Finally,we study Verdier quotient of bounded n-pure derived category modulo the bounded homotopy category of n-pure projective modules,which is called an n-pure singularity category since it can reflect the finiteness of n-pure global dimension of rings.
